The present invention relates to improvements in simulated adipose or fat tissues, products employing these components and processes for preparing them. Although there have been many recent advances in protein technology which have enabled the production of restructured or simulated meat products, there is a current need for a material which can closely simulate natural animal adipose tissue.
In naturally, occurring meats, fat is held in contact with red meat tissue as globules contained within a collagen-based cellular network called adipose tissue. During cooking of the meat, the fat within the adipose tissue is melted and released from the tissue as the cellular structure ruptures. The cooked natural adipose tissue adds a desirable and pleasing juiciness and smoothness to the meat, and the fatty tissue itself will have a melt-in-the-mouth characteristic, which until the present invention, has been exclusively the characteristic of natural fatty tissue.
Due to the high costs associated with the better cuts of meat, there have been many prior art attempts to upgrade less desirable cuts of meat through processing, such as by restructuring. In many of these processes, such as those described in U.S. Pat. Nos. 3,903,315 to Giles et al and 3,904,770 to Hale et al, the meat must be cooked and thus the fat rendered from it prior to restructuring. There is an obvious need in products of this type to restore an adipose tissue component to the meat material after restructuring. Very early attempts to restore adipose tissue did exactly that--they inlaid slabs or slices of fat in the product. Such procedures were, however, costly and demanded a suitable source for fatty material.
In one early attempt to avoid the reliance on natural adipose tissue and yet provide a fat coating to a processed meat product. Eckrich et al in U.S. Pat. No. 2,161,029, disclosed a fat replacement made by homogenizing a mixture of a liquid fat and an aqueous gelatin solution. This material, when cooled, was disclosed to have a consistency approximating that of the white of an egg which has been boiled until it is past the fluid or flowing state. The product becomes flowable on heating to allow application by dipping. In U.S. Pat. No. 2,721,142, Shinn et al also disclosed a procedure for preparing a stable fat containing emulsion for coating meat products. In this case, the stable emulsion contained gelatin and a cellulose gum. The Shinn et al coating, however, like the Eckrich et al material, was not intended to texturally simulate natural adipose tissue but was primarily for the purpose of supplying fat to a fat deficient meat product during cooking and was applied warm by dipping. While these and similar approaches did provide some benefits, the need remained for an adipose tissue simulating material which would provide the attributes of the naturally occurring material.
In addition to work on restructured natural meat as an alternative to high quality fresh meat, there is also an intensive effort being made to develop wholly synthetic meat analogs. There is already an economic incentive for this development, and it is believed in the long term that the solution to the problem of world hunger depends upon man's ability to replace his reliance upon animals as a source of protein, with a direct utilization of the plant protein materials which are inefficiently converted to meat protein by the animals. Accordingly, there has been a major effort in producing meat analogs, and with the exception of a failure to provide a good simulation for fatty tissue, progress towards a true simulation of natural meat has been quite good.
Early meat analog efforts were concerned mainly with simulating the red meat or muscle portion of natural meat and were concerned with only cosmetic similarity as far as the fatty or adipose tissue portion was concerned. For example, in U.S. Pat. No. 3,320,070 to Hartman, there is disclosed a meat-like product consisting essentially of man-made fibers and vegetable protein having zones simulating the appearance of lean portions and natural appearing fat-like portions. The disclosed formation of the fat-appearing portion need not differ from that of the meat portion except through the elimination of red coloring from the white phase portion.
Recently, however, efforts have given attention to both fat and meat portions to provide realistic simulations of their natural counterparts. In U.S. Pat. No. 3,840,677, Leidy et al disclose a simulated, multiphased, meat-like product having distinct regions simulating natural red meat and fat. In one specific embodiment, a bacon analog is disclosed having a fat simulating portion prepared from an aqueous emulsion of fat as the discontinuous phase surrounded by a matrix of heat coagulable protein, containing such proteins as egg albumin, proteinaceous filler materials, soy isolate and other heat settable proteins. Another disclosure of a simulated bacon product is that of Corliss et al, U.S. Pat. No. 3,930,033, which describes a simulated bacon product produced by forming and stacking alternate red and white vegetable protein containing layers to simulate lean meat and fat and then cooking the stacked layers to form a slab. The individual layers are produced from separate aqueous mixtures containing specified amounts of vegetable protein fiber, egg albumin, tapioca starch, water, vegetable oil, vegetable gum such as carageenan, vegetable protein isolate, dextrose, sodium caseinate, colorings, flavors and seasonings. These materials are mixed in an aerating type mixer until the mixture is fully homogenized and a substantial amount of air is entrapped within the maxtrix. This formulation, as with that of Leidy et al, does not provide a juicy, smooth melt-down simulating that of natural bacon fat, but has a more dry and cracker-like texture. The materials of the type disclosed by Corliss et al and Leidy et al, however, make a rather significant improvement over the earlier, purely cosmetic fat-appearing materials.
In another recent attempt to provide a fat containing material for simulating natural adipose tissue in meat or meat analog products, Hawley discloses in U.S. Pat. No. 3,658,550, a fat-containing material based on an insoluble, heat-irreversible alginate gel. The fat containing material is disclosed to respond upon cooking and eating much as does natural adipose tissue. To improve the materials nutrition and browning characteristics, small amounts of protein such as soy, cottonseed, albumin and caseine can be employed. However, while the Hawley material may hold fat and improve the quality of meat or meat-like products having a deficiency of fat and may somewhat visually simulate fat, it lacks the smooth melting and oil release properties of natural adipose tissue.
In some prior art meat analog products, fat was thought necessary as a component, but not necessarily in the form of a distinct adipose tissue phase. Typically, fat was included in these products by simply blending and emulsifying it in the meat forming gel or matrix material. For example, in U.S. Pat. No. 3,108,873 to Durst, a meat-like food product is disclosed to have a "lipophilic fluid" included as a stable dispersion in a film forming composition which may utilize soy protein, wheat protein, wheat germ or egg albumin. Durst also discloses that even hydrophillic colloids such as gelatin, agar, and carboxy-methycellulose have been employed as the film forming composition. Also, in U.S. Pat. No. 3,919,435, Feldbrugge et al disclose a meat analog which contains a vegetable protein gel precursor having incorporated therein a fat or oil entrapped within a thermostable, polymeric carbohydrate gel matrix which may contain proteins such as albumin, casein and whey. By encapsulating the fat in this manner it is protected against emulsification in the gel precursor in the production of a meat analog to result in a juicier product than when the fat is simply admixed without encapsulation. The use of these thermostable gels, however, will leave a dry gritty residue in the mouth if employed in pieces large enough to appear as distinct portions of adipose tissue. Moreover, neither, Durst nor Feldbruggee et al are concerned with or teach a simulated adipose tissue for use as a distinct and separate phase in combination with a meat analog.
Thus, there remains a present need for a simulated adipose tissue which has good nutrition, good cooking properties, a smooth mouthfeel and meltable character upon eating, and also provides a good visual and textural simulation of natural adipose tissue.